1. Field
The disclosed embodiments concern a device for non-destructive control of a component by analyzing distribution of a leakage magnetic field emitted by the component when it is subjected to an exciting magnetic field, comprising means for generating an exciting magnetic field inside the component to be tested, and means for measuring the distribution of the magnetic field emitted by the component in response to the exciting field. The set of means is integrated in a flexible housing to form a device in the form of a flexible coating for being fixed on a region of the surface of the component to be tested. The disclosed embodiments are useful for non-destructive testing (NDT) of aircraft components, but may be used in all industrial sectors where testing the integrity of components is important, such as the automotive, railway, marine, and nuclear industries.
2. Brief Description of Related Developments
In the operation and maintenance of aircraft, it is necessary to employ testing methods that can determine whether the structures have been damaged by cracks or fissures, without harming the parts constituting the structures. The techniques used are jointly referred to as “non-destructive testing” (NDT). NDT techniques are numerous and constantly changing, because the industrial sectors concerned have a need for improved performance from these NDT techniques. The air-transport and civil-engineering sectors are always on the lookout for ever more effective NDT techniques to meet the dual requirements of safety and their desire for cost-reduction.
When dealing with a component made of a non-ferrous metal that is magnetic and conductive, testing techniques are known that are based on Foucault currents. The principle of these techniques resides in using an exciting magnetic field that induces a Foucault current circulation in the component to be tested. The circulation of these induced currents in the component is modified by the presence of defects, fissures, or corrosion. This modification of the distribution of Foucault currents act on the distribution of the magnetic field of the surface of the component generated by the Foucault current. This distribution is generally measured by the induction effect. The information on defects is then extracted from the distribution of the magnetic field.
More recent techniques are also known based on a combination of the exciting magnetic field with a magneto-optical imaging device. The magneto-optical imaging device contains a magnetic material that enables measurement of a generated Faraday rotation that is proportional to the magnetization of the magnetic material in presence of the magneto-optical imaging device from the magnetic field emitted by the component.
All of these means of testing require that the aircraft be immobilized on the ground for the conduct of an inspection of the sensitive areas of the aircraft using the testing apparatus. This entails a relatively long testing period and the presence of a qualified operator, thereby leading to a relatively high maintenance cost.
As far as the designer of this device knows, there is currently no effective means for real time inspecting of the status of structures, e.g., aeronautical structures, throughout their periods of use, and in particular for carrying out an overall evaluation of the health of aeronautical structures while the airplane is in flight.